The purpose of this program project is to determine the biological and environmental contributors to social communicative deficits and skills in autism. This project will investigate genetic, brain mechanisms, and environmental factors with a focus both on differentiating autistic individuals from others and also on accounting for individual differences within the autistic group. The approaches to be used are as follows: 1) an investigation of precursors, correlates, and consequences of social communicative skills in autistic children and adolescents; 2) an experiment aimed at changing social communicative skills in very young children with autism; 3) a genetic study of individuals at risk of autism and associated social communicative deficits because of inverted duplication portion chromosome 15 [invdup(15)]; and 4) a comparison of the neural networks activated in processes involved in communication, including recognition and response to faces, emotions, and prosody, using fMRI with adolescents and young adults with autism and non- autistic language impairment. The results of these studies will have immediate impact on planning intervention to optimize the development of autistic children and long-term impact on discovering the causes and mechanisms involved in the disorder.